Deck Railing Spindle Spacing Calculator
Calculate spindle count and code-compliant spacing.
Last updated: June 2026
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Measure from inside of post to inside of post. Standard section: 96" (8 ft).
Auto-set by type. Override if using non-standard sizes.
IRC building code requires max 4" gap (R318.1.1).
1.5" × 1.5" Wood Square: Standard 1.5"×1.5" wood spindle (baluster). Most common for pressure-treated decks. Cost: $3-$6/each.
Spindle Count & Spacing
Spindles needed16for this section
Actual gap between spindles3.824"(passes IRC code)
Center-to-center spacing5.324"
Total sections (8 ft max)1 section(s)
Material cost$48 - $96
Based on: 96" rail × 1.5" spindle width, max 4" gap. Formula: spindles = floor((length - 2×3.5) ÷ (width + maxGap)), actual gap = (space - spindles×width) ÷ (spindles + 1).
Disclaimer: These estimates are for budgeting purposes only. Actual costs depend on your location, current material prices, and contractor rates. Always get 2-3 quotes from licensed contractors before starting any project.